The objective of this research is to isolate and characterize the as yet unidentified toxins of Atlantic shellfish poisoning caused by the dinoflagellate, Gonyaulax tamarensis, with eventual aims of devising preventive measures or antidotes, and also studying the pharmacological and immunological implications of possible therapeutic use. The toxins for chemical and pharmacological studies will be isolated from the large stock of toxic clams collected in the 1972 and 1974 New England Red-Tide outbreaks and the cells of G. tamarensis which is being successfully cultured. In connection with the above study, the Gulf Coast red-tide Gymnodinium breve toxins will also be studied for comparison.